There are many variants of the plastic ball valve, like […]
There are many variants of the plastic ball valve, like 3-way ball valve and ball valves in different materials. In fact, 3-way ball valve working mechanism is also different from common ball valve. There are many ways to classify valves. Be as it may, there are seven valve components common to all valves.
The body is the framework of the entire ball valve. It acts as a barrier to the pressure load from the media so there is no transfer of pressure to the pipes. It holds all the components together. The body is connected to the piping via threaded, bolted or welded joints. Ball valves can be classified according to the type of body, often cast or forged.
The opening or closing of the valve is provided by the stem. This is also what connects the ball disc to the lever, handle or actuator. The stem is the one that rotates the ball disc to open or close it.
This is the gasket that helps seal the bonnet and the stem. Many of the issues happen in this area so proper installation is important. Too loose, leakage happens. Too tight, movement of the stem is restricted.
The bonnet is the covering of the valve opening. This acts as the secondary barrier for pressure. The bonnet is what holds all the internal components together after these are inserted inside the valve body. Often made from the same material as the valve body, the bonnet can either be forged or cast.
This is the disc of the ball valve. Being the third most important pressure boundary, the pressure of the media acts against the disc when it is in the closed position. Ball discs are often made of forged steel or any durable material. Ball disc can either be suspended like in case of the floating ball valve, or it can be mounted like that of the trunnion-mounted ball valve.
Sometimes called the seal rings, this is where the ball disc rests. Depending on the design of the ball disc, the seat is either attached or not to the ball.
Actuators are devices that create the rotation needed by the ball valve to open the disc. Oftentimes, these have a power source. Some actuators can be remotely controlled so valves still work even if these are located in remote or hard to reach areas.
Actuators can come as handwheels for manually operated ball valves. Some other types of actuators include solenoid types, pneumatic types, hydraulic types, and gears.